Intumescent flame retardant systems have been used in some materials for many years. Traditional intumescent flame retardant systems normally contain three components that are the basic elements to form a char: a source of acid, gas, and carbon. Commercially available intumescent flame retardant systems usually included ammonium polyphosphate (acid donor), pentaerythritol (carbon donor), and melamine (blowing agent). A material containing such a flame retardant system will form a char layer at the surface during combustion to protect the material.
Traditional flame retardant intumescent coatings currently available on the market are intended for interior use. The chemicals used to create the coating are water soluble, which allows the coating to dissolve or reduce performance when subjected to water. For factory applied intumescent coatings, it is unrealistic to assume that the panels will never be exposed to water. Shipping, storage, and rain delays at construction sites provide opportunities for water exposure.